Trailers such as cargo trailers, camping trailers, boat trailers and the like that are used with automobiles and small trucks are often single-axle or bogie trailers that are towed via a tongue (also known as a "drawbar") that is connected to or integral with the chassis of the trailer. The tongue typically has a single-beam or wishbone structure, depending on the load the trailer is to carry. When the trailers are disconnected from the vehicle, a tongue jack is arranged mainly near the front part of the tongue to support the tongue so that it will not rest with its hitch on the ground, and also so that the trailer will stand mainly parallel to the ground to make for easier loading and unloading.
The tongue jack is commonly designed as a threaded rod within a tube so that a supporting wheel or plate can be cranked down to the ground when the trailer is unhitched, or up when it is hitched and ready to be towed. For some trailers, the tongue jack is often removably or pivotably mounted on the tongue by means of a bracket. When the bracket is removed or the jack pivoted up, the jack can be locked clear of the ground and the trailer can be safely towed.
A common problem is that many people forget to retract and lock the tongue jack when the trailer has been hitched to a towing vehicle. When the vehicle then drives away, the tongue jack will sooner or later catch on the ground or road with the result that the entire tongue jack arrangement is deformed or, in the worst case, torn off.
What is needed is an arrangement for tongue jacks that eliminates this risk.